This invention relates to an inkjet printing method, more particularly to a method using a porous ink jet recording element.
In a typical ink jet recording or printing system, ink droplets are ejected from a nozzle at high speed towards a recording element or medium to produce an image on the medium. The ink droplets, or recording liquid, generally comprise a recording agent, such as a dye or pigment, and a large amount of solvent. The solvent, or carrier liquid, typically is made up of water, an organic material such as a monohydric alcohol, a polyhydric alcohol or mixtures thereof.
An ink-jet recording element typically comprises a support having on at least one surface thereof an ink-receiving or image-forming layer. The ink-receiving layer may be a porous layer which imbibes the ink via capillary action or a polymer layer which swells to absorb the ink.
Inkjet prints, prepared by printing onto ink jet recording elements, are subject to environmental degradation. They are especially vulnerable to water smearing and light fade. For example, since ink-jet dyes are water-soluble, they can migrate from their location in the image layer when water comes in contact with the receiver after imaging. Highly swellable hydrophilic layers can take an undesirably long time to dry, slowing printing speed, and will dissolve when left in contact with water, destroying printed images. Porous layers speed the absorption of the ink vehicle, but often suffer from insufficient gloss and severe light fade. Porous layers are also difficult to coat without cracking.
U.S. Pat. No. 4,849,457 discloses a porous membrane for use as a recording medium for ink jet printing comprising a mixture of two water-insoluble polymers and about 9% of polyvinylpyrrolidone. However, there is a problem with this element in that the density obtained with an element having less than about 25% by weight of a water-absorbent polymer is too low, as will be shown hereafter. Further, this membrane is made by coating the two materials from a solvent, and then passing the coated element through a nonsolvent bath. The porous membrane employed in this invention is formed solely upon drying of the coated solution without the need for a nonsolvent bath.
JP95040647A discloses a porous membrane for use as a recording medium for ink jet printing comprising a mixture of a hydrophobic binder containing cationic conductive macromolecules. However, there is a problem with this element in that the density and dye lightfastness obtained with an element having less than about 25% by weight of a water-absorbent polymer is too low, as will be shown hereafter.
U.S. Pat. No. 5,374,475 discloses a porous layer for ink jet printing comprising a thermoplastic polymer free of filler. However, there is a problem with this element in that the density obtained with an element without a water-absorbent absorbent polymer is too low, as will be shown hereafter.
U.S. Pat. No. 5,759,639 discloses a printing medium for ink jet printing which uses a polymeric dope solution. A porous layer is formed using a phase inversion technique. Although a second polymer is used in the process, most of it is washed out in a coagulation step. There is a problem with this element in that the density obtained with an element having less than about 25% by weight of a water-absorbent polymer is too low, as will be shown hereafter.
EP 940,427 discloses a method for making a microporous film for an ink jet recording element in which a hydrophobic polymer and a second hydrophilic polymer or copolymer of N-vinylpyrrolidone is dissolved in a certain solvent system, partially dried, and then washed to extract at least 50% by weight of the second polymer. There is a problem with the elements formed by this process in that a separate washing step is employed which adds to the complexity of the coating process.
It is an object of this invention to provide an ink jet printing method using a recording element which will provide improved ink uptake speed. Another objective of the invention is to provide an ink jet printing method using a recording element having a receiving layer that when printed upon has an excellent image quality.
These and other objects are provided by the present invention comprising an ink jet printing method, comprising the steps of:
A) providing an ink jet printer that is responsive to digital data signals;
B) loading the printer with an ink jet recording element comprising a support having thereon an image-receptive layer capable of accepting an ink jet image comprising an open-pore membrane of a mixture of a water-insoluble polymer and a water-absorbent polymer, the mixture containing at least about 25% by weight of the water-absorbent polymer, the image-receiving layer being made by dissolving the mixture of polymers in a solvent mixture, the solvent mixture comprising at least one solvent which is a good solvent for the water-insoluble polymer and at least one poor solvent for the water-insoluble polymer, the poor solvent having a higher boiling point than the good solvent, coating the dissolved mixture on the support, and then drying to remove approximately all of the solvents to obtain the open-pore membrane;
C) loading the printer with an ink jet ink composition; and
D) printing on the ink jet recording element using the ink jet ink in response to the digital data signals.
Using the method of the invention, a recording element is obtained which will provide improved ink uptake speed and when printed upon has an excellent image quality.
In order for the image-receptive layer to be sufficiently porous, the water-insoluble polymer must be coated from a solvent mixture combination such that an open-pore membrane structure will be formed when the solution is coated and dried, in accordance with the known technique of dry phase inversion. The formation of an open-pore membrane is accomplished by using a mixture of a good and poor solvent for the water-insoluble polymer. As noted above, the poor solvent has a boiling point that is higher than that of the good solvent. When the solution is coated or cast onto a support and dried, the good solvent evaporates faster than the poor solvent, forming the membrane structure of the layer when the polymer phase separates from the solvent mixture. The open-pore structure results when the good solvent and poor solvent are removed by drying.
The water-insoluble polymer that can be used in the invention may be, for example, a cellulose ester such as cellulose diacetate, cellulose triacetate, cellulose acetate propionate or cellulose acetate butyrate, cellulose nitrate, polyacrylates such as poly(methyl methacrylate), poly(phenyl methacrylate) and copolymers with acrylic or methacrylic acid, or sulfonates, polyesters, polyurethanes, polysulfones, urea resins, melamine resins, urea-formaldehyde resins, polyacetals, polybutyrals, epoxies and epoxy acrylates, phenoxy resins, polycarbonates, vinyl acetate polymers and copolymers, vinyl chloride-vinyl acetate copolymers, vinyl chloride-vinyl acetate-vinyl-alcohol copolymers, vinyl chloride-vinyl acetate-maleic acid polymers, vinyl chloride-vinylidene chloride copolymers, vinyl chloride-acrylonitrile copolymers, acrylic ester-acrylonitrile copolymers, acrylic ester-vinylidene chloride copolymers, methacrylic ester-styrene styrene copolymers, butadiene-acrylonitrile copolymers, acrylonitrile-butadiene-acrylic or methacrylic acid copolymers, or styrene-butadiene copolymers. Cellulose ester derivatives, such as cellulose diacetates and triacetates, cellulose acetate propionate, cellulose acetate butyrate, cellulose nitrate, and mixtures thereof are preferred.
The water-absorbent polymer that is used in the invention may be, for example, polyvinylpyrrolidone and vinylpyrrolidone-containing copolymers, polyethyloxazoline and oxazoline-containing copolymers, imidazole-containing polymers, polyacrylamides and acrylamide-containing copolymers, poly(vinyl alcohol) and vinyl-alcohol-containing copolymers, poly(vinyl methyl ether), poly(vinyl ethyl ether), poly(ethylene oxide), hydroxyethylcellulose, hydroxpropylcellulose, hydroxypropylmethylcellulose, methylcellulose, and mixtures thereof.
The choice of a good and poor solvent for the water-insoluble polymer will be effectively determined by the specific choice of polymer. The good solvent that can be used in the invention includes alcohols such as methanol, ethanol, n-propyl alcohol, isopropyl alcohol, isobutyl alcohol, Dowanol(copyright) solvents, glycols, ketones such as acetone, 2-butanone, 3-pentanone, cyclopentanone, and cyclohexanone, ethyl acetate, methylacetoacetate, diethylether, tetrahydrofuran, acetonitrile, dimethylformamide, dimethylsulfoxide, pyridine, chlorinated solvents such as methylene chloride, chloroform, carbon tetrachloride, and dichloroethane, hexane, heptane, cyclopentane, cyclohexane, toluene, xylenes, nitrobenzene, and mixtures thereof.
The poor solvent that can be used in the invention may be, for example, alcohols such as ethanol, n-propyl alcohol, isopropyl alcohol, isobutyl alcohol, 2-methyl-2,4-pentanediol, and Dowanol(copyright) solvents, glycols, ketones such as 2-butanone, 3-pentanone, cyclopentanone, and cyclohexanone, ethyl acetate, methylacetoacetate, diethylether, tetrahydrofuran, acetonitrile, dimethyl-formamide dimethylsulfoxide, pyridine, chlorinated solvents such as carbon tetrachloride, and dichloroethane, hexane, heptane, cyclopentane, cyclohexane, toluene, xylenes, nitrobenzene, water, and mixtures thereof.
After printing on the ink jet recording element, heat and/or pressure can be applied to the element to improve surface gloss, image density and durability. Various methods can be used such as hot presses, hot rolls, hot air, IR-radiation, high frequency heating, and a fusing belt or roller apparatus. For example, the printed element can be passed through a fuser consisting of rollers or a belt and a roller. Temperatures can range from slightly above ambient temperature to an upper temperature limited only by the thermal stability of the support and the membrane components. Temperatures should not be so high as to cause delamination of layers within the support, or any bubbles or defects to form in the support or the open-pore membrane. The heating time is mot limited.
The fusing temperature need not be so high as to be above the glass transition temperature of all of the individual components in the open-pore membrane. Fusing may result in clarification (becoming transparent) or in only partial clarification of the membrane. The degree of clarification need not be identical in printed and non-printed areas of the image or in printed areas of differing density.
The open-pore membrane layer may include low molecular weight or polymeric plasticizers to aid in the fusing step. These plasticizers are compounds that typically have low glass transition temperatures. Plasticizers useful in the open-pore membrane layer include, but are not limited to, poly(ethylene glycol), poly(propylene glycol), chlorinated paraffins such as those sold under the tradenames of Chlorowax(copyright) (Occidental Chemical Corp.) and Paroil(copyright) (Dover Chemical, Inc.), aliphatic polyesters, such as polyester sebacate available commercially as Paraplex(copyright) G-25 from C.P. Hall Co., poly(butylene glycol adipates) available commercially as Drapex(copyright) polymeric plasticizers from Witco Corporation, poly(ethylene succinate), poly(hexamethylene sebacate), or poly(butylene adipate), polycaprolactone, diphenyl phthalate and di(2-ethylhexyl phthalate).
Also, the high boiling components of the inks may remain in the open-pore membrane and aid in the fusing step. Compounds commonly found in ink compositions can also be used to plasticize the open-pore membrane ink receiving layer and facilitate fusing. Examples of such compounds include, but are not limited to, glycols and glycol ethers such as diethylene glycol, diethylene glycol monobutylether, triethylene glycol, dipropylene glycol monomethylether, tripropylene glycol monomethylether, glycerol, Dowanol(copyright) compounds, and poly(ethylene glycol) monobutyl ether; triethanolamine; methyldiethanolamine; 2-pyrrolidone, and N-methyl-2-pyrrolidone.
The plasticizers can be incorporated directly into the coating solution of the membrane, or can be incorporated into the formed open-pore membrane through the printing of the ink which contains these plasticizing compounds or in a printing step prior to printing the inks.
Since the image recording element may come in contact with other image recording articles or the drive or transport mechanisms of image recording devices, additives such as filler particles, surfactants, lubricants, crosslinking agents, matte particles and the like may be added to the element to the extent that they do not degrade the properties of interest.
Filler particles may be used in the open-pore membrane such as silicon oxide, fumed silica, silicon oxide dispersions such as those available from Nissan Chemical Industries and DuPont Corp., aluminum oxide, fumed alumina, calcium carbonate, barium sulfate, barium sulfate mixtures with zinc sulfide, inorganic powders such as y-aluminum oxide, chromium oxide, iron oxide, tin oxide, doped tin oxide, alumino-silicate, titanium dioxide, silicon carbide, titanium carbide, and diamond in fine powder, as described in U.S. Pat. No. 5,432,050.
A dispersing agent, or wetting agent can be present to facilitate the dispersion of the filler particles. This helps to minimize the agglomeration of the particles. Useful dispersing agents include, but are not limited to, fatty acid amines and commercially available wetting agents such as Solsperse(copyright) sold by Zeneca, Inc. (ICI). Preferred filler particles are silicon oxide, aluminum oxide, calcium carbonate, and barium sulfate. Preferably, these filler particles have a median diameter less than 1.0 xcexcm. The filler particles can be present in the amount from about 0 to 80 percent of the total solids in the dried open-pore membrane layer, most preferably in the amount from about 0 to 40 percent.
The open-pore membrane layer may include lubricating agents. Lubricants and waxes useful either in the open-pore membrane layer or on the side of the element that is opposite the open-pore membrane layer include, but are not limited to, polyethylenes, silicone waxes, natural waxes such as camauba, polytetrafluoroethylene, fluorinated ethylene propylene, silicone oils such as polydimethylsiloxane, fluorinated silicones, functionalized silicones, stearates, polyvinylstearate, fatty acid salts, and perfluoroethers. Aqueous or non-aqueous dispersions of submicron size wax particles such as those offered commercially as dispersions of polyolefins, polypropylene, polyethylene, high density polyethylene, microcrystalline wax, paraffin, natural waxes such as carnauba wax, and synthetic waxes from such companies as, but not limited to, Chemical Corporation of America (Chemcor), Inc., Michelman Inc., Shamrock Technologies Inc., and Daniel Products Company, are useful.
The open-pore membrane layer may include coating aids and surfactants such as nonionic fluorinated alkyl esters such as FC-430(copyright), FC-431(copyright), FC-10(copyright), FC-171(copyright) sold by Minnesota Mining and Manufacturing Co., Zonyl(copyright) fluorochemicals such as Zonyl-FSN(copyright), Zonyl-FTS(copyright), Zonyl-TBS(copyright), Zonyl-BA(copyright) sold by DuPont Corp.; other fluorinated polymer or copolymers such as Modiper F600(copyright) sold by NOF Corporation, polysiloxanes such as Dow Corning DC 1248(copyright), DC200(copyright), DC510(copyright), DC 190(copyright)and BYK 320(copyright), BYK322(copyright), sold by BYK Chemie and SF 1079(copyright), SF1023(copyright), SF1054(copyright), and SF 1080(copyright)sold by General Electric, and the Silwet(copyright) polymers sold by Union Carbide; polyoxyethylene-lauryl ether surfactants; sorbitan laurate, palmitate and stearates such as Span(copyright) surfactants sold by Aldrich; poly(oxyethylene-co-oxypropylene) surfactants such as the Pluronic(copyright) family sold by BASF; and other polyoxyethylene-containing surfactants such as the Triton X(copyright) family sold by Union Carbide, ionic surfactants, such as the Alkanol(copyright) series sold by DuPont Corp., and the Dowfax(copyright) family sold by Dow Chemical.
The open-pore membrane layer may include crosslinking agents, such as organic isocyanates such as tetramethylene diisocyanate, hexamethylene diisocyanate, diisocyanato dimethylcyclohexane, dicyclohexylmethane diisocyanate, isophorone diisocyanate, dimethylbenzene diisocyanate, methylcyclohexylene diisocyanate, lysine diisocyanate, tolylene diisocyanate, diphenylmethane diisocyanate; aziridines such as taught in U.S. Pat. No. 4,225,665; ethyleneimines such as Xama-7(copyright) sold by EIT Industries; blocked isocyanates such as CA BI-12 sold by Cytec Industries; melamines such as methoxymethylmelamine as taught in U.S. Pat. No. 5,198,499; alkoxysilane coupling agents including those with epoxy, amine, hydroxyl, isocyanate, or vinyl functionality; Cymel(copyright) crosslinking agents such as Cymel 300(copyright), Cymel 303(copyright), Cymel 1170(copyright), Cymel 1171(copyright) sold by Cytec Industries; and bis-epoxides such as the Epon(copyright) family sold by Shell. Other crosslinking agents include compounds such as aryloylureas, aldehydes, dialdehydes and blocked dialdehydes, chlorotriazines, carbamoyl pyridiniums, pyridinium ethers, formamidinium ethers, and vinyl sulfones. Such crosslinking agents can be low molecular weight compounds or polymers, as discussed in U.S. Pat. No. 4,161,407 and references cited.
The useful thickness range of the open-pore membrane layer used in the invention is from about 1 xcexcm to about 100 xcexcm, preferably from about 2 xcexcm to about 50 xcexcm.
In the present invention, the base support for the open-pore membrane layer of the recording element can be opaque resin coated paper, plain paper, coated paper, synthetic paper, or a transparent material, such as cellulose derivatives, e.g., a cellulose ester, cellulose triacetate, cellulose diacetate, cellulose acetate propionate, cellulose acetate butyrate; polyesters, such as polyethylene terephthalate, polyethylene naphthalate, poly-1,4-cyclohexanedi-methylene terephthalate, polybutylene terephthalate, and copolymers thereof; polyimides; polyamides; polycarbonates; polystyrene; polyolefins, such as polyethylene or polypropylene; polysulfones; polyarylates; polyether imides; and mixtures thereof The papers listed above include a broad range of papers, from high end papers, such as photographic paper to low end papers, such as newsprint.
The support used in the invention may employ an undercoat or an adhesive layer such as, for example, a vinylidene chloride-methyl acrylate-itaconic acid terpolymer or a vinylidene chloride-acrylonitrile-acrylic acid terpolymer. Other chemical adhesives, such as polymers, copolymers, reactive polymers or copolymers, that exhibit good bonding between the open-pore membrane layer and the support can be used. Other methods to improve the adhesion of the layer to the support include surface treatment such as by corona-discharge, plasma-treatment in a variety of atmospheres, UV treatment, etc, which is performed prior to applying the layer to the support.
The recording element used in the invention can contain one or more conducting layers such as an antistatic layer to prevent undesirable static discharges during manufacture and printing of the image. This may be added to either side of the element. Antistatic layers conventionally used for color films have been found to be satisfactory, such as those in U.S. Pat. No. 5,147,768, the disclosure of which is hereby incorporated by reference. Preferred antistatic agents include metal oxides, e.g., tin oxide, antimony doped tin oxide and vanadium pentoxide. These antistatic agents are preferably dispersed in a film-forming binder.
The layers described above may be coated by conventional coating means onto a support material commonly used in this art. Coating methods may include, but are not limited to, wound wire rod coating, knife coating, slot coating, slide hopper coating, gravure coating, spin coating, dip coating, skim-pan-air-knife coating, multilayer slide bead, blade coating, curtain coating, multilayer curtain coating and the like. Some of these methods allow for simultaneous coatings of more than one layer, which is preferred from a manufacturing economic perspective if more than one layer or type of layer needs to be applied. The support may be stationary, or may be moving so that the coated layer is immediately drawn into drying chambers.
Ink jet inks used to image the recording elements employed in the present invention are well known in the art. The ink compositions used in ink jet printing typically are liquid compositions comprising a solvent or carrier liquid, dyes or pigments, humectants, organic solvents, detergents, thickeners, preservatives, and the like. The solvent or carrier liquid can be solely water or can be water mixed with other water-miscible solvents such as polyhydric alcohols. Inks in which organic materials such as polyhydric alcohols are the predominant carrier or solvent liquid may also be used. Particularly useful are mixed solvents of water and polyhydric alcohols. The dyes used in such compositions are typically water-soluble direct or acid type dyes. Such liquid compositions have been described extensively in the prior art including, for example, U.S. Pat. Nos. 4,381,946; 4,239,543 and 4,781,758, the disclosures of which are hereby incorporated by reference.
The following examples further illustrate the invention.